EBK LIFE: THE SCIENCE OF BIOLOGY
11th Edition
ISBN: 8220103935432
Author: Sadava
Publisher: MAC HIGHER
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Chapter 6.3, Problem 3R
Summary Introduction
To review:
The role of cell membrane in maintaining potassium ion (K+) imbalance in neurons and their elimination by K+ membrane channels.
Introduction:
Cells generally have membranes composed of lipids and proteins. The lipids present in the membranes are selectively permeable and does not allow all the substances to enter the cell. The proteins present on the cell membrane form a channel-like structure known as ion channels. Some of these channels are also known as gates.
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Which of the following statements about voltage gated channels is true?
Voltage-gated sodium channels open at a higher (more positive) membrane potential than do potassium-gated channels
Voltage-gated sodium channels open at a lower (more negative) membrane potential than do potassium-gated channels
Sodium- and postassium-gated channels open at about the same membrane potential, but they have different effects because there are different numbers of the two kinds of channels in neuron cell membranes
Fill in the diagram, your illustration should demonstrate for each phase of the AP:
1. The relative concentration of K and Na
2. The relative voltage across the membrane
3. Any movement across the membrane of K and NA
4. The three kinds of channels in the membrane, and their state (open or closed)
5. Finally, indicate on the graph of the AP which phases correspond to hyper- polarization and which phases correspond to de-
polarization
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During neuronal signaling, a change in membrane potential will cause sodium channelsto open and let Na+ ions diffuse down their concentration gradient into the cell. Whichof the following helps establish the concentration gradient necessary for this process tooccur?
Chapter 6 Solutions
EBK LIFE: THE SCIENCE OF BIOLOGY
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- Hyperkalemia is a condition by which ECF potassium levels become too high (usually due to kidney failure). Consider the following questions about the consequence of hyperkalemia on membrane potential. How would hyperkalemia affect EK? Considering your answer to the previous question, how would hyperkalemia affect membrane potential?arrow_forwardThe normal concentrations for intracellular and extracellular potassium in a neuron are [K+]in = 150 mM and [K+]out = 5 mM, respectively. Due to an electrolyte imbalance, a patient has the following intracellular and extracellular concentrations of potassium: [K+]in = 140 mM and [K+]out =2 mM. Using the Nernst equation (Chapter 4), calculate the equilibrium potential for potassium in the cells with normal K+ distributions and of the diseased patient. Refer back to Question #1. Will it be easier or more difficult to generate an action potential in the diseased neuron as compared to the normal neuron? Why?arrow_forwardIf a cell with the following ion concentrations had a resting membrane potential of -40mV which of the following can you conclude? Extracellular: Cl- = 110 mM, Na+ = 145 mM, K+ = 5mM. Intracellular Cl- = 20 mM, Na+ = 10 mM, K+ = 140mM a) At rest it is only permeable to potassium b) At rest it has some permeability to more than one of these ions c) At rest it is only permeable to chloride d) Rest it is not permeable to sodiumarrow_forward
- What happens to the membrane potential inside and outside of the cell when K+ channels are open?arrow_forwardWhich of the following is the most important contributor to the difference between the resting membrane potential and the equilibrium potential of potassium? A B Influx of Ca++ ions Influx of Cl- ions с D Influx of Na+ ions Electrogenic effect of Na+/K+ pumparrow_forwardWhich of the following statements best describes the features of voltage-gated K+ channels? They consist of 4 subunits, are activated at the same time as voltage-gated Na+ channels, but do not inactivate. They consist of 4 subunits, are activated by depolarisation and close slowly during the refractory period. They have 24 membrane spanning alpha helices, 4 of which have positively charged amino acids which promote a conformational change in the channel following depolarisation. They consist of 4 subunits and are open at rest which causes the resting membrane potential to be close to the K+ equilibrium potential.arrow_forward
- 1.A poison causes a drastic rise inE value with stimulation of the membrane.Thereafter membrane is slow to return towards resting membrane potential and levels off several millivolts above the threshold potential. This poison has likely affect which feature of the membrane? a) voltage gated na+ channels. b) voltage gated K+ channels. c) Na+/K+ Atp pump 2. All cell membrane demonstrate action potential if stimulated enough? True/False. 3. how many peaks are there in a compound action potential? a)2. b)4 c)6 d)8 4. Increasing the ionic concentration in the salt bridge results in E value increase to a point after which it plateeus. This is evidence brownian movement at work in the ionic solution that is keeping from energy flowing through the bridge with the fidelity that is seen in the metal bridge? True/ False 5. All cell membrane demonstrate action potential if stimulated enough? True or False.arrow_forwardChoose the correct answer: A) When the voltage gated K+ channels open K+ moves down its concentration gradient from the ECF to inside the cell. O B) The value for resting membrane potential is closer to the EK+ (Equilibrium potential for K+) than the ENa+ O C) When the membrane potential is at rest the membrane is more permeable to Na+ than it is to K+ O D) Closing of the voltage-gated Na+ channels increases the permeability of the membrane to Na+arrow_forwardWhat happens across the membrane of an electrically active cell is a dynamic process that is hard to visualize with static images or through text descriptions. View this animation (http://openstaxcollege.org/l/dynamic1) to learn more about this process. What is the difference between the driving force for Na+ and K+? And what is similar about the movement of these two ions?arrow_forward
- What happens to the membrane potential when Na+/K+ pump is active?arrow_forwardIf sodium permeability were to increase compared to normal what would be the resulting effect on the membrane potential 1.The charge on the inside of the cell becomes less negative compared to resting conditions and hyperpolarizes 2.The charge on the inside of the cell becomes more negative compared to resting conditions and hyperpolarizes 3.The charge on the inside of the cell becomes less negative compared to resting conditions and depolarizes 4.The charge on the inside of the cell becomes more negative compared to resting conditions and depolarizesarrow_forwardWhat is the equilibrium membrane potential due to Na+ ions if the extracellular concentration of Na+ ions is 154 mM and the intracellular concentration of Na+ ions is 23 mM at 20 ∘C ?arrow_forward
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